Page 23
ComfortSense
t
Model L7742U Touch Screen 7−Day Programmable Thermostat
Dehumidification
(continued)
ComfortSense
®
Model L7742U thermostat operation
with Humiditrol enabled
Cooling only
Dehumidification will only occur if:
S
a dehumidification demand is present,
S
a cooling demand is not present,
S
outdoor temperature is less than 95ºF,
S
indoor temperature is not cooler than 65ºF or cooler than the heat-
ing se 2ºF (
IF
the difference between cooling and heating
setpoints is greater than the deadband).
In this case, 24 VAC is removed from the D" terminal and Y1 & Y2"
terminal (if available) becomes activated with 24VAC. This cycles the
indoor variable speed motor to the dehumidification speed and cycle Y2
ON" to the outdoor unit. Cooling has priority over Humiditrol
®
calls.
Heating only
Thermostat will cycle heating ON" and OFF to main-
tain heating setpoint. Dehumidification functions are disabled.
Autochangeover
Dehumidification will only occur if a dehumidifica-
tion demand is present, a cooling demand is not present, outdoor tem-
perature is less than 95
°
F, indoor temperature is above 65
°
F and the
indoor temperature is not cooler than 2ºF above heating setpoint.
In this case, the 24 VAC is removed from the D" terminal and the Y1 &
Y2" terminal (if available) becomes activated with 24VAC. This will
cycle the indoor variable speed motor to the dehumidification speed
and cycle Y2 ON" to the outdoor unit. Cooling calls have priority over
Humiditrol
®
calls. Humiditrol
®
mode is allowed to overcool up to 2
°
F
above the heating setpoint.
Note: If the last thermostat demand was a heating demand, the thermo-
stat does not require a cooling demand before Humiditrol
®
operation.
Humidification Sensor Fault
If the humidification sensor fault occurs, then the H terminal becomes
inactive, and the D terminal goes to 24V.
Dew point adjust is only available when an outdoor sensor is attached.
Other Humiditrol
®
EDA Notes:
If the outdoor sensor is disconnected while HUMIDITROL is enabled,
the thermostat will not allow operation in dehumidification mode.
Set point range: 45 to 60% Relative Humidity (RH). Factory default −
50%.
Relative Humidity controls to within 2% on either side of RH set point.
When the D" terminal is activated with 24VAC, dehumidification is in-
active.
BASIC, PRECISION and HUMIDITROL
modes are deactivated by de-
fault from the factory.
As a precaution, regardless of how low the heating setpoint has been
set, Humiditrol
®
dehumidification is inhibited below 65
º
F indoor temper-
ature.
